INFORMATION, DUCTING

If you intend to join an existing duct system, there may
be two ways to go:

IF THE WARM AIR DUCTS ARE METAL, then it MIGHT be possible
to feed directly into the warm air ducts. Then the JUCA
system would be totally independent of the other heating
system. There are some things to watch for during
installation. Join the duct system at its thickest point.
Make sure JUCA heat ONLY goes toward the rooms and not backwards
back into the furnace. Make sure that if the power goes out and
the JUCA air gets much hotter, that the metal of the ducts
would not cause nearby wood to catch fire.

IF THE COLD AIR RETURNS ARE METAL ONLY (NOT METAL PANNED
JOISTS, ETC.), then it MIGHT be possible to feed into the
other furnace's cold air return. In this case, the JUCA
blower will only have to move it's air TO the cold air
return, where the other furnace's blower picks it up and distributes
it from there (without that furnace's burner being on).
There are even more safety considerations to consider when
using this approach. As above, it is critically important
that hot air cannot go the wrong way in ducts and that, during
power outages, that no nearby wood could catch fire due to the
air in the ducts being much hotter.

IF THE DUCTS ARE NOT ALL METAL, THEN IT MAY NOT BE SAFE TO
USE THEM. CONSULT YOUR LOCAL BUILDING INSPECTOR.
Sometimes there is STILL a way to combine the efforts of the JUCA
and the conventional furnace blower. If that furnace has a major COLD
AIR RETURN that is near the JUCA, then the JUCA could JUST send its
heat into the rooms adjacent to itself, and the conventional furnace's
BLOWER could be turned on to draw that warmed air from that room,
and without further heating it, distribute that heat throughout the
whole house. A manual way to do this is to just go to that furnace's
wall thermostat and move the sub-base's FAN switch to its ON or SUMMER
FAN position from its normal AUTO position. There is also a simple
way to automate this, to close this switch whenever the JUCA blower
turns on, while still allowing it to work normally whenever the other
furnace's burner needs to turn it on.

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Whichever way you intend to hook up the ducting, make
sure to have a heating contractor do the work.
He will know all the safe procedures necessary to keep you
and your family safe. Also, make
sure that you take into account that the first 10 feet
of hot air ducting MUST be insulated from any wood.

Reasonable air flow and heat delivery requires certain
planning that must be done for your particular application.
Each house is unique and so is its ducting system.
That's another reason for having a local heating contractor
do this work. Even if we would try to give guidance over the
phone, it would ONLY be general, and might not apply because
of unique aspects of YOUR house.

Elbows and angle fittings in both directions are
standard available items for the size ducting that JUCAs feed.

The warm air outlet on a JUCA is either 8"x16" or 8"x12"
to directly be able to join modern main heating trunk lines. IF YOUR DUCTS
ARE NOT ALL METAL THEN IT MAY NOT BE SAFE TO USE THEM FOR ANY SOLID
FUEL HEATER. Consult your local building inspector. We strongly recommend
that only a knowledgeable person plan and install the duct connection.
We are sure that you join us in wanting a very, very safe installation
in your house. We know we're repeating ourselves here. Get it?

FEEDING INTO WARM AIR DUCTS:

This allows the JUCA and the other furnace to be totally independent
of each other but generally requires one of our optional blowers (to
duplicate the air circulation capability of the other furnace blower.
Join the existing system at or near its thickest section (probably
near the other furnace). A check-flow damper may need to be installed
(See Check-Flow Damper) to eliminate
back flow through either furnace whenever the other one is operating.
Of course, it must not stop warm air that is trying to leave either
furnace (for example, if BOTH try to operate at the same time),
and only keep air from going backward into either.

This connection method involves considering installing air filters
and a humidifier in the JUCA air path, because its air does NOT go
through those features of the other furnace. JUCAs are compatible
with ALL standard air filters and humidifiers.

Another way sometimes used

Sometimes people try to feed the JUCAs warm air into the warm air
ducts with our standard blower and then operate their other furnace
blower to pick it up from there and spread it through the house ducts. This
will only work if the joining point is very carefully designed so
that it has the effect of a venturi
section (like a carburetor works in a car). Otherwise, what happens
is that the bigger furnace blower tends to try to push air backward
through that new connecting duct, back into the JUCA and the JUCAs air
will tend to get very hot since it has no place to go. If you choose
to try this, and find that the outer shell of the JUCA is too warm
to continuously touch, you probably have this problem.

This "alternate" type of connection is a little
more complicated than it first seems even though it is a way recommended
by some of our competitors (we think, incorrectly). The ONLY
appropriate ways to do this involve EITHER getting the JUCA blower
that is about the same size and capacity as the blower in the other
furnace (so it can't be over-powered) OR to design the connecting
point to have a "venturi effect" as mentioned above. If
this is done correctly, the air flow of the other (big) blower,
is capable of causing a "sucking" action to actually help
pull the JUCA's warm air out into its path.

If you do use this method, you should check the JUCA's hood
temperature when operating. If it is hotter than allowing you to
hold your hand against it, then probably the air is not being able
to leave the stove properly and some change in the connection area
is necessary.

FEEDING INTO A COLD AIR RETURN:

The two furnace blowers work in "series" in this installation. The
JUCA heats the air then sends it to the other furnace where it is
mixed with some unheated air then pushed through without its burners
being on. You use the other furnace blower to do the bulk of the
work of circulating throughout the house, but the JUCA blower is
still necessary to get the heated air to the other furnace blower.
It is very important to make sure that the JUCAs heated air cannot
overheat anything. Study every place that hot air could wind up,
even backwards in the ducting system.

When the JUCA is operating, the air in the cold air return duct is
drawn into the JUCA, heated up there, and then put back into that
same cold air return duct (after the BAFFLE shown). Then the JUCA-warmed
air proceeds to and through the other furnace's blower, on its way
to the house ducts. ONLY the blower
of the conventional furnace operates (NOT the burner, so no fuel
is used). That (large) blower does most of the work of distributing
the JUCA-warmed air throughout the house.

This configuration still requires at least the standard blower
to operate on the JUCA. The other furnace's blower is not designed
to "suck" the air through the JUCA, as that would cause
something bad called "cavitation."

When the JUCA is NOT operating, the conventional furnace pulls MOST of
its air by its original path, past the BAFFLE, and pulls the remainder
through the JUCA heat exchanger path. The conventional furnace
operates normally.

It would also be possible to make the BAFFLE motorized. Then, the
cold air return duct would remain totally unobstructed for the
normal operation of the conventional furnace, and the BAFFLE would
swing out and divert most of the air through the JUCA air path
when the JUCA blower turns on. The motor of that damper would
just be wired in parallel with the JUCA blower, so it would turn
on and close at the correct times.

This general arrangement's air path ALWAYS passes through the
conventional furnace's air filter system and humidifier.

A SEPARATE DUCT SYSTEM

Of course, it would be possible to install a duct system JUST for
the JUCA. If the house currently didn't have warm air ducts, this
may be the way to go. There could be some other extenuating circumstances
that suggest going this way. The heating contractor will have the
best vantage point on just which way to go.

Sometimes, in houses
that currently don't have ducts, people operate the JUCA for one
winter, to see how much of the house can be heated to the comfort level
desired, without ducting. If the results are satisfactory, then
nothing else would ever need to be done. But, if it was found that
a single distant bedroom or bathroom was not warm enough, it would be
possible to run one small duct the following year, to get some
extra heat to that area. JUCAs are amazingly flexible in such ways!

AN UN-DUCTED DUCT SYSTEM!

Finally, there may be yet another approach to consider. IF the house
has a good conventional furnace system, AND if that system has a large
COLD AIR RETURN INTAKE near the JUCA, then consider the following.
Use the JUCA to JUST send its warm air into the area around it (without
feeding into the house heating or duct system.) Then, use the
"SUMMER FAN" switch on the sub-base of the wall thermostat
of the conventional furnace to turn JUST THE BLOWER on. (Not the burner.)
The warm air that the JUCA is creating in the room that it is in, will
then be drawn into the Cold Air Return and therefore be distributed
to all the rooms of the house. Without ACTUALLY being connected into
the house duct system!

It would even be possible to automate this kind of installation
with a Relay as described below.

Notes

Relay

In some of the installations described above, the blower of the
conventional furnace is used to help distribute the heat throughout
the house. It could be left ON (controlled manually)
with its "SUMMER FAN" switch (on the sub-base of the wall
thermostat for that furnace) or it could be hooked up to turn on
normally and/or with the JUCA. A simple, inexpensive RELAY could be
bought locally. It should be a 110-volt COIL, relay, with SPST
contacts, as mentioned below.

The following describes a "NON-invasive" method
of connection that does NOT involve doing anything inside the other
furnace. The SPST relay would be used. The coil of this relay
would be wired in parallel with the JUCA's blower motor, so the relay
would be actuated whenever the JUCA blower was on.

The SPST switch contacts would be wired in
parallel with the 24-volt circuit SUMMER FAN switch in the
sub-base of the conventional furnace's wall thermostat. The effect would
be so that the SUMMER FAN circuit would be automatically closed, just as
if you manually moved that switch on the sub-base. This method does NOT
invade the other furnace, so it does not affect any warranties or anything!

Other Notes

The bypass duct and the opening past the BAFFLE (in the Cold
Air Duct Feed method) can be VERY important to allow the other furnace
to operate properly when the JUCA wasn't being used. This is especially
important if the JUCA blower is smaller than the blower on the
other furnace. The filters,
humidifier, etc of the other furnace work for both in this
installation. The initial cost might be less (a smaller JUCA blower
could be used) but electricity for two blowers will eventually make up
for that.

MAKE ABSOLUTELY SURE THAT ALL OF THE FIRST 10 FEET OF WARM AIR DUCTING
FROM THE JUCA IS INSULATED FROM ANY WOOD OR OTHER COMBUSTIBLES, EVEN IF
IT MEANS MODIFYING EXISTING DUCTWORK.

If the JUCA is installed in an unheated space, then a cold air
return MUST be provided for the JUCA. There are a LOT of good
reasons for this. Trust us!

If ducts pass through an unheated basement or crawlspace,
they should be insulated with Fiberglas insulation, to minimize
heat loss in those ducts, just like with any other furnace.

It is extremely important to measure the "Static Pressure
Levels" and air flow rates. Otherwise, any or all of several
problems could occur.

The existing furnace may wind up pushing a
load level it is not adjusted for. (Either too high OR too low!)
That could be hard on that blower's motor.

The JUCA blower may wind up pushing against a duct pressure
load outside of it's allowable range of operation (see the chart below.)

The two blowers may wind up fighting each other.

Some rooms may get a lot of warmed JUCA air while others get less.

These are some of the reasons why a professional duct person should at least
oversee the installation of the duct system, or you need to get a
duct pressure guage to find the values in your system.